This Phase I application aims at developing a generalizable electrochemical biosensing platform for detection of metal ions in water. Specifically, the main objective of the project is to validate the design of a convenient, cost-effective electrochemical ion (E-ION) sensing platform for direct detection of metal ion contaminants such as mercury (Hg2+), silver (Ag+), and copper (Cu2+) in drinking water. While previously developed metal ions sensors have been demonstrated to possess exceptional sensitivity and selectivity, no generalizable sensor architecture that is applicable to the detectin of a wide range of metal ions has been realized to date. The E- ION sensor's signaling mechanism relies on the dampening of the DNA recognition probe dynamics upon target binding which involves inter-strand metal complexation, thereby creating a sensor that is inherently signal-off when interrogated using alternating current voltammetry. However, by varying the applied frequency in square wave voltammetry, these sensors can be converted into signal-on sensors, which is, in general, more desirable. More importantly, these sensors will be fabricated on a gold-plated screen-printed carbon electrode array, enabling them to be mass-produced at relatively low cost. The sensitivity and selectivity of these sensors should be comparable to current optical approaches, while offering the improved stability, reusability and operational convenience of direct electrochemical detection. Our ultimate goal is to develop an inexpensive biosensor array to monitor levels of metal ion contaminants in drinking water. The real-world applicability of the sensor array will be validated by demonstrating sensitive and selective detection of Hg2+, Ag+, and Cu2+ in real household water samples. Successful completion of the proposed project will provide consumers with an economical and simple method to ensure water quality for both drinking and other household applications. The proposed research could have a major positive impact on human health and quality of life, especially for those who reside in relatively low resources, rural and remote areas.